The chemical products resulting from manufacture of metallurgical coke in by-product coke ovens are of significant economic benefit in coke-plant operation inasmuch as the gases, light oil, and tar are valuable raw materials for the plastics, pharmaceutical, and agricultural industries. It is well known that variations in coke-oven operation with regard to operating conditions, design, and coal-charge characteristics have an effect on the amount and type of the products produced.
The principal criterion for coke-plant operation is the production of high-grade metallurgical coke at the lowest possible cost. Therefore, the chemical products that are realized from by-product coke ovens cannot be readily controlled and are subject to variation as a result of the changes in demand for coke. It is desirable to be able to increase the yield of certain chemicals, such as ethylene, when the coke-oven operating rate may be low or high, thereby ensuring an adequate supply to ethylene feedstocks (i.e., ethylene, ethane, propane propylene, propadiene or the like) for operation of chemical facilities based on these raw materials.
Earlier attempts to increase the chemical yield of coke ovens involved changes in operating conditions, such as oven temperatures, coal charge, bulk density, chemical addition to the coal, oil addition to the coal, water addition to the coal, and the like. In general, these techniques had relatively small effects on the chemical yield unless a very large change was made to the variable, and in such a case, a significant deleterious change resulted in the quantity or quality of the coke produced. Furthermore, th cost of adding materials to the coal charge frequently exceeded the value of the incremental chemical yield. In addition, the inclusion of materials in the oven charge generally results in decreasing the amount of coal placed in the oven, thereby reducing the coke production, and also upsets the heat requirement for the completion of coking. Finally, any change in the chemical yield should be such that the general character of the by-products is unchanged inasmuch as the chemical plant facilities associated with the coke ovens have been designed for a previously specified product distribution although it is desirable to be able to vary the proportions of the by-products particularly to be able to increase the proportion of ethylene feedstocks.
Conventional apparatus and methods are shown in the following patents:
______________________________________ U.S. Patent No. Inventor Issued ______________________________________ 1,530,631 VanAckeren 3/24/25 2,006,115 Shaefer 6/25/33 2,018,664 Fritz et al 10/28/35 2,065,288 Otto 12/22/36 ______________________________________